1. Field of the Invention
The present disclosure pertains to the use of lactic acid bacteria as a feed supplement to enhance the feed performance and to reduce pathogenic infection in an animal, such as a ruminant. More particularly, the disclosure relates to a unique combination of low dose and high dose bacteria supplement to enhance feed performance and to reduce pathogenic infections in the animal.
2. Description of Related Art
Pathogens have been known to cause illnesses in animals, including humans. Pathogens may cause a wide variety of illnesses ranging from mild disorders to fatal diseases. Examples of such illnesses include weight loss, diarrhea, abdominal cramping, and renal failure, among others.
Extreme health risks may result when humans consume food products that have been contaminated with pathogens. Food products that are most vulnerable to such contamination include sprouts, lettuce, meat products, unpasteurized milk and juice, and water, among others. The problem is particularly prevalent in the beef and dairy industry. Pathogens present on a cow's udder or on milking equipment may find their way into raw milk. Meat can become contaminated at the slaughter house, and pathogenic organisms can be mixed into large quantities of meat when it is ground. This problem is difficult to solve because contaminated meat often looks and smells perfectly normal. Furthermore, the number of pathogenic organisms needed to cause disease is extremely small, and detection of such small number of pathogens is extraordinarily difficult.
Pathogens that cause diseases in the intestinal tract are commonly known as enteropathogens. Examples of enteropathogenic bacteria include Staphylococcus aureus, certain strains of Escherichia coli (E. coli), and Salmonella spp. While most of the hundreds of strains of E. coli are harmless and live in the intestines of animals, including humans, some strains, such as E. coli O157:H7, O111:H8, and O104:H21, produce large quantities of powerful shiga-like toxins that are closely related to or identical to the toxin produced by Shigella dysenteriae. These toxins can cause severe distress in the small intestine, often resulting in damage to the intestinal lining and resulting in extreme cases of diarrhea. E. coli O157:H7 can also cause acute hemorrhagic colitis, characterized by severe abdominal cramping and abdominal bleeding. In children, this can progress into the rare but fatal disorder called hemolytic uremic syndrome (“HUS”), characterized by renal failure and hemolytic anemia. In adults, it can progress into an ailment termed thrombotic thrombocytopenic purpura (“TTP”), which includes HUS plus fever and neurological symptoms and can have a mortality rate as high as fifty percent in the elderly.
Food borne pathogen contamination may be controlled by minimizing contamination at several points of entry by pathogens. Pre-harvest control of pathogens by the beef industry such as by reducing pathogen shedding in feces, has been recognized as an important point of control. Beyond this point, pathogens can find many different ways into the food chains, for example, through potential runoff contamination, contact with humans, or cross contamination during meat processing.
U.S. Pat. No. 7,063,836 disclosed a unique combination of lactic acid producing bacterium and lactate utilizing bacterium as feed supplements (also known as direct-fed microbials (DFM) or probiotics) to help reduce pre-harvest infections in ruminants. The compositions and methods disclosed in U.S. Pat. No. 7,063,836 help reduce the numbers of enteropathogens such as E. coli O157:H7. By reducing the numbers of enteropathogens in animals that produce meat or milk, these methods help protect consumers of beef, dairy, and other food products from being infected by the pathogens.
A number of studies have been conducted to determine the effects of different dosages of the DFM on feed performance and pathogen reduction. Stephens et al. compared the recovery of E. coli O157 or Salmonella in cattle fed with the low (107), medium (108) and high (109) dose of Lactobacillus acidophilus/animalis NP51 (also known as LA51, or NPC747), in conjunction with 1×109 CFU of Propionibacterium freudenreichii NP24 (also known as PF24). Journal of Food Protection, Vol. 70, No. 10, Pages 2386-2391 (2007). Above the dosage of 107 CFU per animal per day, no significant dose-response of NP51 on recovery of E. coli O157 or Salmonella was detected when used in conjunction with a fixed dosage of PF24. Thus, according to Stephens et al., the low and high doses were about equally effective in reducing the recovery of E. coli O157. Id. at p2390. For reduction of Salmonella, the high dose of NP51 supplementation appeared to be the most effective among the three doses in reducing Salmonella in feces or on hides of feedlot cattle. Id. In a separate study, Vasconcelos et al. reported that the dosage of NP51 has no significant effects on average daily weight gain when used in conjunction with a fixed dosage of PF24. J. Animal Science, 86:756-762 (2008). In fact, feed performance, as measured by carcass-adjusted gain to feed ratio (G:F) and dressing percentage, decreased with increasing dosage of the NP51 when used in conjunction with a fixed dosage of PF24. Id. These studies all point to a conclusion that the ideal DFM program for improving biological performance of feedlot cattle would have a different dosage of DFM than the ideal program for reducing the numbers of pathogenic bacteria. Thus, at the time of the present invention, it appeared impossible to have a single program that meets both goals of achieving high feed performance while reducing pathogenic bacteria.